SNOMED CT

SNOMED CT is a comprehensive clinical terminology that provides clinical content and expressivity for clinical
documentation and reporting. SNOMED CT contains concepts for both human and non-human medicine and
some of the covered domains are:

• Clinical findings, including disorders
• Procedures, broadly defined as including all health related activities.
• Observable entities which, when given a value, provide a specific finding or assertion about health related
information.

SNOMED CT can be used in health care software applications that focus on collection of clinical data, linking
to clinical knowledge bases, information retrieval, as well as data aggregation and exchange.

LOGICAL MODEL

The SNOMED CT logical model provides the fundamental structure of SNOMED CT and specifies how the components can be managed in an implementation setting to meet a variety of primary and secondary uses.

Relationship

For diseases/disorders, SNOMED CT uses relationships between concepts to provide logical, computer readable definitions of medical concepts. There are several types of relationships described or modeled in SNOMED CT.

The SNOMED CT logical model provides the fundamental structure of SNOMED CT and specifies how the components can be managed in an implementation setting to meet a variety of primary and secondary uses.

Concepts

Every concept represents a unique clinical meaning.

Descriptions

A set of textual descriptions are assigned to every concept.

Relationships

A relationship represents an association between two concepts.

Snomed CT Relationship

"Is A" Relationship

The “Is A” relationship is used to create a hierarchical relationship between concepts, relating specific concepts to a more general category. For example:
"Injury to the optic nerve"
"is a" (kind of)
"Injury to the visual pathway"

"Finding Site" Relationship

The "Finding Site" relationship identifies the part of the body affected by the specific disorder or finding. For example:
"Injury of cornea"
(has) "finding site"
"Corneal structure"

"Causative agent" Relationship

The "Causative agent" relationship identifies the direct cause of the disorder or finding. The causative agent is the bacterium, virus, toxin or environmental agent that causes the disorder. For example:
"Staphylococcal eye infection"
(has) "Causative agent"
"Staphylococcus"

"Associated morphology" Relationship

The “Associated morphology” relationship identifies the abnormal physical condition that is characteristic of a given disorder or finding. For example:
"Foreign body under eyelid"
(has) "Associated morphology"
"Foreign body"

"Procedure Site" Relationship

The "Procedure Site" relationship identifies the part of the body acted on by the procedure. For example:
"LASIK"
(has) "Procedure site"
"Corneal structure"

"Method" Relationship

The "Method" relationship identifies the kind of procedure that is being carried out. For example:
"Removal of foreign body from eye"
(has) "Method"
"Removal"
"Grafting of fascia of eyelid"
(has) "Method"
"Transplantation"

"Direct Morphology" Relationship

"Direct Morphology" Relationship
The "Direct Morphology" relationship identifies the abnormal physical condition that is being directly addressed by the procedure. There is an implicit link between the "method" relationship and the direct morphology. The method acts on the direct morphology. For example:
"Removal of foreign body from eye"
(has) "Direct morphology"
"Foreign body"

"Direct Device" Relationship

The "Direct Device" relationship identifies the device that is involved in the core operation of the procedure. An example of the direct device relationship is as follows:
"Removal of eye prosthesis"
(has) "Direct device"
"Eye prosthesis"